I've had a tablet for a year now (Samsung Galaxy Tab 3 8") and I find it very useful.
But a month ago I bought a new Sony Smart-tv for my bedroom and I'm amazed at how much having a tablet with certain apps make it so much easier to use the tv for accessing e.g. Youtube videos and media on my home network. Things that the tv itself could do but which becomes so much more accessible with a tablet.
Sony has an app "TV SideView" which makes it possible to find and play content from DLNA servers on my home network, including my Panasonic digital recorder in the living room. It can also be used to program recordings on the tv and many other things.
I can also use Synology DS Video and DS Audio apps on my tablet to play video and music from my Synology NAS to my tv, and other apps to view pictures.
I bought a Google Chromecast and attached it to my older tv to get some of the same possibilities in the living room.
I didn't really expect devices from different manufacturers (Sony, Samsung, Panasonic, Google, Synology) to play so well together and I'm quite pleased.